(a) Field of the Invention
The present invention relates to a photoresist remover composition used to remove photoresist during the manufacture of semiconductor devices such as large-scale integrated circuits (LSI), and very large-scale integrated circuits (VLSI).
(b) Description of the Related Art
Generally, a photoresist pattern forms on a conductive layer of a semiconductor device during the manufacturing process of semiconductor devices, and then a part of the conductive layer, which is not covered with the pattern, is etched by repetitive lithography processes using the pattern as a mask, to form a conductive layer pattern. The photoresist pattern used as the mask should be removed from the conductive layer by using a photoresist remover during a stripping process performed after the formation of the conductive layer pattern. However, the recent processes in manufacturing very large-scale integrated circuits have adopted a dry etching process to form a conductive layer pattern, thus removing a photoresist during the next stripping process becomes difficult.
The dry etching process, opposed to a wet etching process using acidic chemical solution, is performed through a gas-solid reaction between a plasma etching gas and a material layer such as a conductive layer. The dry etching process is easily controllable and produces a sharp pattern, and thus it is currently leading the trend in etching processes. However, during the dry etching process of the conductive layer, ions and radicals of the plasma etching gas have a chemical reaction with the photoresist layer at the surface of a photoresist, so that the photoresist layers rapidly cured. Accordingly, removing the photoresist becomes difficult. Especially, on the stripping process, cured side-wall photoresist polymer which is produced from a conductive layer such as aluminum, aluminum alloy, and titanium nitride during the dry etching process has difficulty in being removed by most kinds of photoresist remover.
As earlier photoresist removers of the conventional stripping process, a photoresist remover composition obtained by mixing an organic amine compound and various organic solvents has been suggested, in particular a photoresist remover composition containing monoethanolamine (MEA) as an essential organic amine component has been widely used.
For example, a two-component photoresist remover composition consisting of a) an organic amine compound such as monoethanolamine (MEA) and 2-(2-aminoethoxy)ethanol (AEE), and b) a polar solvent such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), carbitol acetate, and methoxyacetoxypropane (disclosed in U.S. Pat. No. 4,617,251); a two-component photoresist remover composition consisting of a) an organic amine compound such as monoethanolamine (MEA), monopropanolamine, and methylamylethanol, and b) an amide solvent such as N-methylacetamide (MAc), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N-diethylacetamide (DEAc), N,N-dipropylacetamide (DPAc), N,N-dimethylpropionamide, N,N-diethylbuthylamide, and N-methyl-N-ethylpropionamide (disclosed in U.S. Pat. No. 4,770,713); a two-component photoresist remover composition consisting of a) an organic amine compound such as monoethanolamine (MEA), and b) a non-protonic polar solvent such as 1,3-dimethyl-2-imidazolidinone (DMI), and 1,3-dimethyl-tetrahydropirimidinone (disclosed in German Patent Laid-Open Publication No. 3,828,513); a photoresist remover composition, in predetermined mixing ratio, consisting of a) an alkanol amine such as monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) and alkylene polyamine substituted by ethylene oxide of ethylenediamine, b) sulfolane or sulfone compound, and c) glycol monoalkyl such as diethylene glycolmonoethyl ether and diethylene glycolmonobutyl ether (disclosed in Japanese Patent Laid-Open Publication No. Sho 62-49355); a photoresist remover composition consisting of a) water-soluble amine such as monoethanolamine (MEA) and diethanolamine (DEA), and b) 1,3-dimethyl-2-imidazolidinone (disclosed in Japanese Patent Laid-Open Publication No. Sho 63-208043); a positive photoresist remover composition consisting of a) amines such as monoethanolamine (MEA), ethylenediamine and benzylamine, b) a polar solvent such as DMAc, NMP and DMSO, and c) a surfactant (disclosed in Japanese Patent Laid-Open Publication No. Sho 63-231343); a positive photoresist remover composition, in predetermined mixing ratio, consisting of a) nitrogen-containing organic hydroxyl compound such as monoethanolamine (MEA), b) one or more solvents selected from a group of diethayleneglycol monoehthylether, dietyleneglycol dialkylether, γ-butylolactone and 1,3-dimethyl-2-imidazolinone, and c) DMSO (disclosed in Japanese Patent Laid-Open Publication No. Sho 64-42653); a photoresist remover composition consisting of a) an organic amine compound such as monoethanolamine (MEA), b) a non-protonic polar solvent such as diethylene glycolmonoalkyl ether, DMAc, NMP and DMSO, and c) a phosphate ester type surfactant (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-124668); a photoresist remover composition consisting of a) 1,3-dimethyl-2-imidazblinone (DMI), b) dimethylsulfoxide (DMSO), and c) organic amine compound such as monoethanolamine (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-350660); and a photoresist remover composition consisting of a) monoethanolamine (MEA), b) DMSO, and c) catechol (disclosed in Japanese Patent Laid-Open Publication No. Heisei 5-281753) have been suggested, and these photoresist remover compositions have excellent characteristics in safety, working efficiency and photoresist removing performance.
However, in recent processes for manufacturing semiconductor devices, there are trends toward hard-baking processes at high temperatures where various layers, as well as silicon wafer, are treated at a high temperature. The photoresist remover compositions of the above examples do not have the sufficient ability to remove the photoresist hard-baked at high temperatures. Thus, a photoresist remover composition containing water has been suggested to remove the photoresist hard-baked at high temperatures. For example, a photoresist remover composition consisting of a) hydroxylamine, b) alkanolamine, and c) water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 4-289866); a photoresist remover composition consisting of a) hydroxylamine, b) alkanolamine, c) water, and d) an anticorrosive (disclosed in Japanese Patent Laid-Open Publication No. Heisei 6-266119); a photoresist remover composition containing a) a polar solvent such as GBL, DMF, DMAC and NMP, b) amino alcohols such as 2-methylaminoethanol, and c) water (disclosed in Japanese Patent Laid-Open Publication No. Heisei 7-69618); a photoresist remover composition containing a) amino alcohols such as monoethanolamine (MEA), b) water, and c) butyldiglycol (disclosed in Japanese Patent Laid-Open Publication No. Heisei 8-123043); a photoresist remover composition containing a) alkanolamines and alkoxyalkanolamines, b) glycol monoalkyl ether, c) sugar alcohols, d) a quaternary ammonium hydroxide, and e) water (disclosed in Japanes Patent Laid-Open Publication No. Heisei 8-262746); a photoresist remover composition containing a) one or more alkanolamines selected from monoethanlolamine or AEE, b) hydroxylamine, c) diethyleneglycolmonoalkyl ether, d) sugars (sorbitol), and e) water (disclosed in Japanese Patent Laid-Open Publication No. 9-152721); and a photoresist remover composition consisting of a) hydroxyl amine, b) water, c) amines having an acid dissociation constant (pKa) of 7.5˜13, d) a water-soluble organic solvent, and e) an anticorrosive (disclosed in Japanese Patent Laid-Open Publication No. Heisei 9-96911) have been suggested. However, the above photoresist remover compositions have been examined to find that they are insufficient to remove a side-wall photoresist polymer changed in quality due to exposure to a plasma gas during the dry-etching process, or ashing process, that is used to manufacture very large-scale integrated circuits (VLSI). Thus, it is necessary to develop a photoresist remover that can be used in the dry-etching process.
As mentioned above, it is difficult for a conventional photoresist to remove the photoresist having been on the dry-etching process. The surface of the photoresist layer is cured by the heat generated from the reaction due to a high radiation dose and high energy of ion beams. At the same time, additionally, a photoresist residue may be produced due to a phenomenon of photoresist popping. Generally, the wafer on the ashing process is heated at 200° C. or higher. At this time, the solvent remaining in the photoresist should be exhausted, which is not possible because a cured layer exists on the surface of the photoresist after the ashing process.
Thus, as the ashing process is performed, the internal pressure of the photoresist layer increases and the surface of the photoresist layer pops due to the solvent existing therein, which is called popping. The cured layer formed on the surface of photoresist scatters and it is difficult to remove the resultant residue from the cured layer. In addition, the photoresist changes to residues and particles and acts as a contaminant, thereby lowering yield in VLSI chip production. Particularly, in order to effectively remove the photoresist, performing the ashing process before the stripping process makes the photoresist change more excessive, thus increasing the failure ratio of semiconductor devices during the stripping process.
Various etching processes have been suggested in order to effectively remove the cured photoresist layer described above, and among them, a two-stage ashing process has been disclosed by Fujimura in a pre-announcement for the Japanese Applied Physics Association in Spring (page 1˜13, and page 574, 1389). According to the two-stage ashing process, ashing is first performed by a general method, and then a second ashing process is performed. However, these processes are complicated and require very large-scale equipment, thereby lowering the efficiency of the process.
Finally, this problem can be solved in the stripping process using an aqueous photoresist remover composition. A photoresist remover composition consisting of a hydroxylamine, an alkanol amine, an anticorrosive and water has recently been suggested and is widely used, since it has a relatively good removal characteristic to the cured photoresist. However, this photoresist remover composition has an under-cut, which is produced from corrosion to a new metal layer adopted to a 64 Mega-DRAM or more DRAM-semiconductor production line. Thus, development of a new photoresist remover that can address the fault is required.